NIH study highlights the need to proactively screen for, prevent, and treat cannabis use disorder especially among young people.
A scientific study has found a strong association between cannabis use disorder and the development of schizophrenia, particularly among young men aged 21-30. Up to 30% of schizophrenia cases in this group may have been prevented by averting cannabis use disorder.
Young men with cannabis (marijuana) use disorder have an increased risk of developing schizophrenia, according to a study led by researchers at the Mental Health Services in the Capital Region of Denmark and the National Institute on Drug Abuse (NIDA) at the National Institutes of Health. The study, published in Psychological Medicine, analyzed detailed health records data spanning 5 decades and representing more than 6 million people in Denmark to estimate the fraction of schizophrenia cases that could be attributed to cannabis use disorder on the population level.
Researchers found strong evidence of an association between cannabis use disorder and schizophrenia among men and women, though the association was much stronger among young men. Using statistical models, the study authors estimated that as many as 30% of cases of schizophrenia among men aged 21-30 might have been prevented by averting cannabis use disorder.
Cannabis use disorder and schizophrenia are serious, but treatable, mental disorders that can profoundly impact people’s lives. People with cannabis use disorder are unable to stop using cannabis despite it causing negative consequences in their lives. Schizophrenia is a serious mental illness that affects how a person thinks, feels, and behaves. People with schizophrenia may seem like they have lost touch with reality, and the symptoms of schizophrenia can make it difficult to participate in usual, everyday activities. However, effective treatments are available for both cannabis use disorder and schizophrenia.
“The entanglement of substance use disorders and mental illnesses is a major public health issue, requiring urgent action and support for people who need it,” said NIDA Director and study coauthor Nora Volkow, M.D. “As access to potent cannabis products continues to expand, it is crucial that we also expand prevention, screening, and treatment for people who may experience mental illnesses associated with cannabis use. The findings from this study are one step in that direction and can help inform decisions that health care providers may make in caring for patients, as well as decisions that individuals may make about their own cannabis use.”
Previous studies indicate that rates of daily or near daily cannabis use, cannabis use disorder, and new schizophrenia diagnoses are higher among men than women, and that early, frequent cannabis use is associated with an increased risk of developing schizophrenia. However, few studies have examined differences in the relationship between cannabis use disorder and schizophrenia across different sex and age groups at the population level.
To address this research gap, investigators analyzed data from nationwide health registers in Denmark, which included health records data from more than 6.9 million people who were aged 16-49 at some point between 1972 and 2021. Using these nationally representative longitudinal data, the researchers investigated how the associations between cannabis use disorder and schizophrenia varied by different sex and age groups, and how these differences changed over time.
Although there are many risk factors associated with schizophrenia, in this study, researchers sought to estimate the proportion of all schizophrenia cases that may be attributed to cannabis use disorder specifically, across sex and age groups at the population level. The study team estimated that 15% of cases of schizophrenia among men aged 16-49 may have been avoided in 2021 by preventing cannabis use disorder, in contrast to 4% among women aged 16-49. For young men aged 21-30, they estimated that the proportion of preventable cases of schizophrenia related to cannabis use disorder may be as high as 30%. The authors emphasize that cannabis use disorder appears to be a major modifiable risk factor for schizophrenia at the population level, particularly among young men.
This study also adds to existing evidence suggesting that the proportion of new schizophrenia cases that may be attributed to cannabis use disorder has consistently increased over the past five decades. The authors note that this increase is likely linked to the higher potency of cannabis and increasing prevalence of diagnosed cannabis use disorder over time.
“Increases in the legalization of cannabis over the past few decades have made it one of the most frequently used psychoactive substances in the world, while also decreasing the public’s perception of its harm. This study adds to our growing understanding that cannabis use is not harmless, and that risks are not fixed at one point in time,” said Carsten Hjorthøj, Ph.D., lead author of the study and associate professor at the Mental Health Services in the Capital Region of Denmark and at the University of Copenhagen.
The authors note that further research is needed to examine potential differences in the potency and frequency of cannabis consumption between young men and women, and to examine the mechanisms underlying the higher vulnerability of young men to the effects of cannabis on schizophrenia. The association of cannabis potency with cannabis use disorder and psychosis may help inform public health guidelines; policies on cannabis sales and access; and efforts to effectively prevent, screen for, and treat cannabis use disorder and schizophrenia.
Reference: “Association between cannabis use disorder and schizophrenia stronger in young males than in females” by Carsten Hjorthøj, Wilson Compton, Marie Starzer, Dorte Nordholm, Emily Einstein, Annette Erlangsen, Merete Nordentoft, Nora D. Volkow and Beth Han, 4 May 2023, Psychological Medicine.
For more information on substance and mental health treatment programs in your area, call the free and confidential National Helpline 1-800-662-HELP (4357) or visit www.FindTreatment.gov.
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This isn’t cause and effect though is it? I can posit many reasons they would be associated. For example perhaps people who are at risk of abuse have some disorder which also predisposes them to schizophrenia?
People with mental disorders are predisposed to addiction, from the preponderance of evidence I’ve seen, whether from vulnerability or self-medicating. You should see the number of psychiatric inpatient smokers.
Still, it does seem to be cause and effect in other studies. This particular study is garbage. “Cannabis Use Disorder” was one of the major changes that made the DSM-5 absurd — the American Psychiatric Association that publishes it may as well add “Psychiatric Associating Disorder”. That said, there appears to be evidence that youths predisposed to schizophrenia may trigger its onset early or even avoidably by using cannabis before the brain has developed by their mid-twenties and particularly if male. I don’t want it to be true, and it needs more study for confirmation, which is difficult when NIDA blocks it as illegal. I would advise a friend to only use low doses until over 25, or with a family history of schizophrenia to avoid cannabis entirely until older. In any case, all things people do have risk, especially teens, and cannabis has a multitude of benefits to weigh against the few risks, and my free advice is worth the price.
Using this kind of research to control people is evil, and scitechdaily is prey to politically-motivated ‘research’. NIDA published this, and they are the shaft of the spear of the American drug war, with a vested interest in maintaining prohibition. NIDA was essentially created under Nixon to support the drug war with pseudoscience and prevent research that wouldn’t link drugs to harm. This study says under Financial Support “This study received no funding.”, which is hilarious, an unfunded study, done for free and also worth that price. I would file this under Half Truths & Manipulations, along with a third of stories on SciTechDaily unfortunately, but two thirds of the cannabis stories.
I don’t really think matijuana can be excluded as a cause, because marijuana can also be used to treat certain mental conditions as well. So like any drug, overuse can cause unwanted side effects.
The connection occurs often enough to say there’s something to cannabis (over?)use and drug induced psychosis, how much it is predisposed by qnother condition is anyone’s guess, given how well we do science today (we constantly introduce our own biases)
DRUG WAR PROPAGANDA…I have successfully treated emotional disturbance and associated schizophrenia with cannabis for years. I am sure there is a link, not that cannabis’s caused the illness but because many of us use marijuana in a medical capacity to successfully treat the disorder; The old drug war perpetuators would have you believe Marijuana causes the problem. This is just one more example of how they twist the facts.
If you have any 2 of 11 criteria you qualify as having the disorder. #5 is desire to use cannabis. #10 is developing tolerance, where you use a bit more to get as high. Since any regular use evidences #5, and generally #10, congratulations, you’re disordered.